Looking for advice on my Ahri build :)

I&#039;ve started playing Ahri and would like her to become my mid main whenever I play mid, and since I like calculating and optimising my builds, I wrote down all the parts of it for you to check out and give me your advice on what to change and what is good. :)
**Summoner Spells:**
{{summoner:12}} or {{summoner:14}} and {{summoner:4}}
**Runes:**
Marks: +7.8 Magic Penetration
Seals: +9 Armor
Glyphs: +12 Magic Resist
Quints: +15 Ability Power
**Masteries:**
http://shrani.si/f/3l/jU/CjOqIb8/ahri-masteries.png
**Items:**
{{item:3020}} {{item:3165}} {{item:3089}} {{item:3285}} {{item:3157}} {{item:3001}}
**Stat bonuses from items, runes and masteries:**
+648 Ability Power
+10 Attack Damage
+400 Mana
+45 +10% Movement Speed
+54 Armor
+72 Magic Resist
+23 +7% Magic Penetration (rounded up from 22.8)
+UNIQUE Passives (Rabadon&#039;s Deathcap passive has already been calculated into the total AP value)
It&#039;s a generic build, which would protect me against mixed damage, while also having **40% CDR** and having a total of **648 Ability Power**.

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